EV styles

P. Edward KnickKnack said:
Actually, after the Rivian towing thread, I was wondering why EV cooling for a vehicle that can tow is not up to the same design standards as ice vehicles? Ice puts out a lot of heat, but they cool it down. I guess it is 100 year old companies who have been building trucks as long as there have been trucks, they know how to build trucks. As in trucks that tow up hills.
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The batteries are not easy to cool due to the thermal path radially through the sides. The center of the battery can be far hotter than the perimeter. I think Rivian uses 2170's which are known to have even more difficulty with heat transfer issues vs 18650's due to the larger diameter. As I understand it, even full immersion cooling with "jets" of oil that actively cool the cells is insufficient under high rate charge/discharge conditions.

Tesla developed the 4680 "tabless" cell to help address some of these issues. Not only can the cell produce and charge with far more current without heating up, but these cells can be configured to transfer heat through the bottom and sides.

Worth reading:

www.enpowerinc.com

Tesla Battery Day – EnPower’s Take – EnPower, Inc.

Everyone is talking about Tesla's Battery Day. Here's EnPower's take on Tesla's mission, technology announcements, and what it means for the future of EVs.
www.enpowerinc.com www.enpowerinc.com
 
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P. Edward KnickKnack said:
Actually, after the Rivian towing thread, I was wondering why EV cooling for a vehicle that can tow is not up to the same design standards as ice vehicles? Ice puts out a lot of heat, but they cool it down. I guess it is 100 year old companies who have been building trucks as long as there have been trucks, they know how to build trucks. As in trucks that tow up hills.
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Based on my understanding, the cooling need of an ICE engine for the same output to the wheel is much higher than EV. Typical gas engine has 15-30% efficient at most, maybe 39% for Prius, probably way less for a pickup truck with V8. However an electric motor has probably 75%-90% efficiency and the efficiency loss is at the power plant burning natural gas or nuclear reaction. So obviously your cooling need is 1/3 to 1/5 as much as a gas engine.

ICE engine would not only need a radiator but also a lot of air going under the hood to cool around the engine. EV need coolant flowing through motor, battery, inverter, etc but not to the same temperature or degree of the engine. You can keep it cool by letting less air into the bay or just turn it into a frunk, and shrink the grill size 2/3, and it will be just as good. If you seal the engine up and not let air go around it, relying only on coolant flow, you probably will overheat it.

I've seen experiment of putting radiator in the rear of the EV and seal the front, but that ran into airflow problem. Keeping a small radiator in the front seems to be the best option so far. There's a compromise between cooling and aerodynamics.

For Rivian they probably should limit the towing speed instead of letting it overheat towing uphill.
 
PandaBear said:
Keeping a small radiator in the front seems to be the best option so far. There's a compromise between cooling and aerodynamics.
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Many EVs use automatic louvres to block airflow into the radiator and AC when not needed to reduce drag. There's very little heat loss from the motor and driver hardware.
 
meep said:
I just want a regular looking vehicle.
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If there was an affordable/realistic conversion for my 1997 Explorer when the SOHC 4.0 bites the dust, I'd be all for it. I could drive the truck forever, don't really care how it gets down the road as long as it does.
 
Traditional all day every day. I’m not against modernization of the automobile but putting every feature into a screen or button sequence will become frustrating when you just need to make a quick adjustment.

Minimalistic design is not always the most functional. You’re paying more for less.
 
avacado11 said:
Traditional all day every day. I’m not against modernization of the automobile but putting every feature into a screen or button sequence will become frustrating when you just need to make a quick adjustment.

Minimalistic design is not always the most functional. You’re paying more for less.
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After driving the Model 3, our Lexus cars seem overly complicated, almost confusing with myriad of buttons.
The Tesla has voice controls to handle many functions.
"Set the temp to 72" sets the temperature.
"My butt is cold" adjusts the heated seat up. You can use the 3 letter version as well.
"Navigate to blah-blah-blah" gets you there.
There is so much more and you get new stuff all the time.

Minimalistic design takes some getting used to and is not for everyone, I can tell you that.
One thing it has over manual controls is the ability to get better via OTA updates.
 
JeffKeryk said:
Minimalistic design takes some getting used to and is not for everyone, I can tell you that.
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The mark of a brilliant engineer is to greatly simplify a complex situation.

Here is how the Brittish do landing gear:
maxresdefault.jpg

VS:
1646837841738.jpeg



Although, there is often a very valid reason behind conventional design. The air vents in the Tesla are ingenious for sure. However, here in Hot-n-Sticky South Florida, I really enjoy aiming all 4 F150 vents at me, and cranking the AC to MAX. I'm not interested in the truck automatically controlling the temp, I'm interested in blasting myself with cold air.


A bit of clarification with regard to battery cooling. I think I was not clear. It's not the size of the cooling system that is the problem. It is the discharge/charge rate that heats the center of the battery. The best solution with today's batteries, is to have a bigger battery pack and pull less power from each cell. Tesla's "Track Mode" supposedly pre-cools the battery, for a bit of extra time before it runs into thermal limits. An interesting work-around, but fails to solve the issue. On an actual track, 4 (admittedly epic) laps may be all you get before the battery gets hot and the power gets reduced.

Take the Model 3 performance with it's 82Kwh battery pack and 450 (or so) HP and reduce HP to 200 or maybe even 250. I'll bet a dollar the battery pack remains within thermal limits for an entire track event. Or just double the size of the battery.
 
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As much as I hate to stereotype, there is some truth to the severe and often bizarre styling of some EV's being purposeful and to call attention to the drivers who may in fact be wanting to "virtue signal". And that may be more important to those drivers than attractive styling.

But then again there sure are a lot of butt ugly ICE cars these days. Honda's and BMW's being particularly overly styled or looking like a 10 year old with a Pep Boys gift card started adding on all kinds of non functional scoops and grilles.

The Tesla Model S is very attractively styled. The Models 3 and Y look like a baby Beluga whale. I don't know if 60 years from now that the styling of some of those vehicles will be looked upon with the same kind of nostalgia that car collectors have for tail fins or a lot of chrome or will they have an Edsel like reputation ?
 
DwightFrye said:
The Tesla Model S is very attractively styled.
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I agree! I find it to be a very nice shape, a professional looking sedan. Without being overly fancy, laden with chrome or superfluous add-ons.

And it even looks great on the racetrack!

model-s-plaid.jpg

Just for kicks, it needs two oval exhaust pipes exiting in front of the rear wheel....
 
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